Update default value for index.translog.flush_threshold_size

[markwalkom]

Per the recommendation here - http://www.elasticsearch.org/blog/performance-considerations-elasticsearch-indexing/ - can/should we set index.translog.flush_threshold_size to 1g by default in latest releases?

[clintongormley]

@markwalkom not sure it is always appropriate. It increases indexing throughput, but also increases recovery time in case of shard failure.

@mikemccand what do you think?

[mikemccand]

That's a good point (higher recovery time); the blog post should have mentioned that tradeoff. It does also mean added disk usage.

But then, fsync is often quite costly on the IO system, and if you are indexing with enough client side concurrency, you can burn through 200 MB quickly enough (I've seen that equate to ~ 5 seconds wall clock time). Maybe we should increase to 500 MB?

[clintongormley]

Seems reasonable to me

[kimchy]

@mikemccand I see you pushed it, should this also go to 1.5? I think it should, no?

[mikemccand]

@kimchy OK, I agree ... I'll push.

[mikemccand]

This was fixed in 1.5.0